The Great Melt

History
The Great Melt was an event that began somewhere around 2260 AD and lasted over a decade. After the destruction of the majority of the world, a climate shift (to some extent caused by a minor change in Earth's tilt) resulted in a melting of a number of large Alaskan glaciers. The flooding, and subsequent famine due to loss of crops, shelter, and livestock, resulted in the deaths of millions, mostly refugees who had managed to reach Alaska from other regions. It caused the abandonment of most small towns in Alaska, erased a lot of the history of the Old World, and resulted in the concentration of survivors in the remaining cities.